Function createFinalization

lib/internal/process/finalization.js:15–146

()

const { emitExperimentalWarning } = require('internal/util');

function createFinalization() {
  /**
   * @type {SafeFinalizationRegistry}
   */
  let registry = null;

  const refs = {
    __proto__: null,
    exit: [],
    beforeExit: [],
  };

  const functions = {
    __proto__: null,
    exit: onExit,
    beforeExit: onBeforeExit,
  };

  function install(event) {
    if (refs[event].length > 0) {
      return;
    }

    process.on(event, functions[event]);
  }

  function uninstall(event) {
    if (refs[event].length > 0) {
      return;
    }

    process.removeListener(event, functions[event]);

    if (refs.exit.length === 0 && refs.beforeExit.length === 0) {
      registry = null;
    }
  }

  function onExit() {
    callRefsToFree('exit');
  }

  function onBeforeExit() {
    callRefsToFree('beforeExit');
  }

  function callRefsToFree(event) {
    for (const ref of refs[event]) {
      const obj = ref.deref();
      const fn = ref.fn;

      // This should always happen, however GC is
      // indeterministic so it might not happen.
      /* istanbul ignore else */
      if (obj !== undefined) {
        fn(obj, event);
      }
    }